Reversible hydride thermal energy storage cell optimized for solar applications

ABSTRACT

A solar energy collection and storage system and a method of collecting and storing solar energy. The system includes a device for focusing solar energy onto a reaction chamber for the conversion of metal hydride to liquid metal and hydrogen, a metal/metal hydride chamber containing a metal/metal hydride mixture, a hydrogen storage system using hydrides and a thermo-cline for recovering the thermal energy from the hydrogen when it is cooled from 2000 F to ambient conditions for storage.

FIELD OF INVENTION

This invention relates to a solar energy collection and storage systemand more particularly to a solar energy collection and storage systemwhich converts solar energy into thermal energy storing the energy inthe heat of formation of calcium hydride.

BACKGROUND

Solar energy provides a thermal power source which can supply asignificant fraction of the world energy needs. A complete system whichcan absorb the sunlight during the day and produce continuouselectricity provides a benefit to the society. Large scale solar powerproduction, in GWatt quantities, is the focus of this patent. A powertower concept provides a solution where a central receiver absorbssunlight from a field of mirrors focused on the tower. The Barstowfacility, Solar 1 and 2, provides an example of this type of facility.For extended operation a thermal storage medium of potassiumnitrate/sodium nitrate salts allow several hours of extended run timebeyond the daylight hours. These systems use the heat of fusion withinthe salt, ie when a material transitions from a liquid to a solid, asthe storage medium. The energy density of the salt mixture requiressignificant quantities of salts to provide a few extra hours ofoperation due to the low energy density.

SUMMARY

Providing continuous electricity from solar significantly increases thebenefit and usefulness of this energy source. This invention utilizesthe heat of formation between calcium and hydrogen to form calciumhydride as the energy storage medium. Calcium hydride provides up to 20times the energy density of the solar 1 and 2 salt systems.

Calcium hydride is chosen due to its ability to be broken apart using athermal heat source; such as the sun. The process is endothermicabsorbing the suns energy during the day and storing it chemically. Theprocess is reversed at night with the calcium and hydrogen recombiningto form calcium hydride in an exothermic reaction. The direction of thereaction is controlled by the temperature and pressure in the reactionchamber. Calcium hydride is one of the more stable hydrides and willoperate reversibly in the 1200 F to 2200 F temperature range. At thesetemperatures a Stirling engine or supercritical CO2 Brayton cycle can beused, integrated with a heat pipe, to produce electricity from thethermal storage.

The hydrogen, separated during the daytime, is stored in a separate lowtemperature hydride tank which allows a low cost bulk storage techniquefor the hydrogen. Titanium iron hydride provides a low cost storagesolution for the hydrogen.

Heat exchangers with thermal storage can be used to store the heat whenthe hydrogen is cooled from temperatures of approximately 2000 F to 100F. A method for storing the thermal energy from the hydrogen is to use athermo-cline filled with boron oxide and dispersed graphite fibersplaced perpendicular to the hydrogen flow heat exchanger. The top of thethermo-cline remains at high temperature while the bottom remains at alower temperature. Hydrogen flows between two manifolds located withinthe thermo-cline within a series of tubes dispersed within the boronoxide to transfer thermal energy to and from the hydrogen. When thehydrogen flows from the reactor to the storage it is cooled by the boronoxide. When the hydrogen flows from the storage to the reactor it isheated by the boron oxide. A second method for storing the hydrogenthermal energy uses a high temperature boron oxide liquid counter-flowheat exchanger which provides an efficient solution to recover themajority of the heat from the hydrogen. A second low temperature counterflow heat exchanger, using a nitrate salt mixture, can also beintegrated to extract more of the energy from the hydrogen.

The advantage of this system is that it is a completely reversibleclosed cycle. The intermittent sunlight can be chemically stored andreleased at a controlled rate for electric power production. The systemuses materials which are low cost and provide a competitive electricalproduction facility for both small and very large scale application.

BRIEF DESCRIPTION (OF THE FIGURES)

FIG. 1 depicts a reversible hydride thermal energy storage systemcoupled with a thermally driven generator in a down mirrorconfiguration. From left to right, the four components displayed are acooled tank containing hydride hydrogen storage cylinders, a thermoclineheat exchanger double tank, a calcium hydride thermal storage cell(directly below the down mirror structure), and a 100 kW Stirling enginedriven electrical power generator.

FIG. 2 depicts a reversible hydride thermal energy storage systemcoupled with a thermally driven generator in a direct beam heatingconfiguration. The components are identical to FIG. 1 as describedabove, excepting that the down mirror is omitted and a black body heatpipe is incorporated at the top of the calcium hydride storage cell.

FIG. 3 is a solar thermal storage system flow chart useful forvisualizing how the system operates when in discharge mode, after thesun has set.

FIG. 4 is a solar thermal storage system flow chart useful forvisualizing how the system operates when in charging mode, when the sunis shining.

DETAILED DESCRIPTION

The storage system consists of three tank systems: The first is thecalcium and calcium hydride storage cell (1) with reaction chamber. Thesecond is the hydrogen storage tanks (2) using a low temperaturetitanium iron hydride material. The third tank provides thermal storageused for extracting the energy from the hydrogen prior to the hydrogenbeing stored in the low temperature hydride tanks (2). A singlethermo-cline tank is used to store the hydrogen energy as it cools from2000 F to near room temperature. This embodiment uses a high temperaturedouble tank (17) to cool the hydrogen from 2000 F to 100 F. This thermalstorage tank combination is also used to heat the hydrogen prior to itentering the calcium cell (1).

FIG. 1 shows an embodiment of a three tank system. The calcium/calciumhydride tank (1) consists of an outer tank (3 a), a mid tank (3 b), andinner tank (4) with an insulation layer (6) between the three tanks. Theinner tank (4) is maintained at temperatures of 1500 F to 2000 F whilethe outer tank (3 a) is slightly above room temperature. The insulation(6) maintains a minimal heat loss between the three tanks. The innertank (4) contains the two materials calcium and calcium hydride. Thecalcium floats above the calcium hydride. Above 1800 F both materialsare liquid. The insulation layer (6) extends completely around bothinner tank (4) and mid tank (3 b) including the top and bottom.

The mid shell serves as a containment shell for the liquids duringoperation. The temperature drop through the insulation is sufficient sothat the mid tank (3 b) operates below the melting point of Calcium. Ifa leak occurs the liquid Calcium freezes prior to reaching the mid tank(3 b). The use of silicon dioxide insulation is due to the reactionwhich occurs with the liquid Calcium. Free silicon will form whichsolidifies stopping the reaction. Calcium oxide powder provides an inertlayer between the mid tank (3 b) and inner tank (4).

The reaction between calcium and hydrogen to produce calcium hydride isexothermic. This provides the heat source to drive a thermal engine suchas a Stirling engine, Brayton turbine, or steam turbine. Calcium,calcium hydride, and hydrogen gas are in equilibrium with the hydrogenpressure a function of the reaction temperature. At approximately 1800 Fthis equilibrium is 1 atmosphere pressure. At 2000 F this isapproximately 3 atmospheres pressure. The system pressure andtemperature combination is used to create either an exothermic orendothermic reaction between the 3 components.

The level of calcium and calcium hydride, within the inner tank (4),varies depending on the state of charge of the thermal cell. A fullycharged cell is all calcium with hydrogen stored separately. A fullydischarged cell is all calcium hydride. Hydrogen is used to pressurizethe three tank regions within cell (1); including the lid (5).

A hydrogen inlet and outlet line (11 a) is located in the top of thecalcium/calcium hydride tank (1). A bolt flange (14 a), at the top oftanks (3 a), and (3 b) join together to seal the two tanks. A watercooled lid (5) maintains o-ring seal temperatures. A quartz window (15)is located on the top of the calcium/calcium hydride tank (1), in lid(5), so that sunlight can project onto the reaction chamber (9). Thereaction chamber (9) is fabricated of a molybdenum lanthanum oxidematerial. The inner surface of the reaction chamber (9) is chromiumplated to protect the molybdenum from oxidation if air enters into thereaction chamber (9) while at high temperature and to provide a lowemissivity surface for the sunlight absorption after the chromiumplating is oxidized. A series of helio-stat mirrors located on theground around the solar thermal reaction tower are focused on a downfacing mirror, which is attached to the top of a down mirror tower, andwhich is located above the calcium/calcium hydride tank (1) and focusessunlight through the quartz window (15). The area between the quartzwindow (15) and the reaction chamber (9) does not have insulation.Argon, nitrogen gas or a vacuum fills the reaction chamber (9).

A means of filling the inside of the reaction chamber (9) withinsulation reduces heat loss at night. A movable set of plates, fittedwithin the reaction chamber (9), could be setup to close the region withinsulation at night. During the day the plates would move in an outwarddirection to allow a clear space between the quartz window (15) and thereaction chamber (9). An alternative would be to have a hinged insulatedor reflective lid which closes over the quartz window (15) during thenight.

The inner tank (4) is made of molybdenum with Lanthanum oxide dispersedwithin the metal which raises the recrystallization temperature abovethe metal operating temperature. Remaining below the recrystallizationtemperature is very important to the strength and toughness of themolybdenum. The outer tank (3 a) is made of a low temperature stainlesssuch as 304 or 316. The mid tank (3 b) is made of a high temperaturestainless such as RA330 or Haynes 230. A Rhenium layer (16) is coated onthe inside of the inner tank (4). This Rhenium layer (16) provides abarrier between the Calcium or calcium hydride and the braze junctionsused to fabricate the molybdenum tank (4). If the molybdenum parts canbe fabricated without seams, or with e-beam welds, then the Rheniumcoating layer is not required. The inner tank (4) is fabricated fromsheet stock and is brazed together at the side, top, and bottomlocations. The molybdenum is machined to provide a tapered overlappingjoint for brazing. A chromium layer is electroplated at the jointlocations. The parts are brazed with a Cobalt-Palladium alloy to providesealed junctions. Once the brazes are complete the Rhenium is appliedlocally over the braze junction with a thickness of approximately 0.004inches on the inner tank surface. In order to enhance the e-beam weldingcharacteristics of the molybdenum an addition of 10% to 40% Rhenium canbe added. As an alternative the inner tank (4) could be fabricated froma ceramic material such as calcium aluminate or calcium oxide. Thematerial could have a molybdenum lanthanum oxide wire mesh distributedwithin the ceramic wall to increase the inner tank strength and preventlarge cracks from forming. The insulation between tank (4) and (3 b) canbe a powder fill of calcium oxide or it can be a rigid insulation suchas silicon dioxide or aluminum oxide.

The hydride tanks (2) are used to hold the hydrogen at ambienttemperature. The tanks contain a solid porous material which allowsrapid hydrogen transport in and out of the porous material. A chemicalbond is created within the material which creates a metal hydride.Titanium iron hydride is chosen for this application as ambienttemperature low cost material. Over 1% hydrogen by weight is absorbedwhen the hydride is created. Hydrogen is absorbed and released whenmaintained between 0 C and 50 C. The hydrogen pressure varies withtemperature. As the temperature is raised the pressure rises to severalatmospheres. A flowing water heat exchanger tank (8) surrounds thehydride tanks (2) and maintains the hydride powder temperature duringthe hydrogen absorption and desorption processes. The hydrogen movementresults in either an exothermic or endothermic reaction. When hydrogenis added to the titanium iron powder thermal energy is released into thewater bath (8). When hydrogen is removed from the titanium iron hydridethermal energy is added from the water bath into the hydride powder tomaintain the hydrogen pressure.

The thermo-cline double tank (17) is used to store the hydrogen thermalenergy when it is being cooled from approximately 2000 F to 100 F. Thethermo-cline tank uses the specific heat of liquid boron oxide to storethe hydrogen energy. The high temperature dual tanks (17) operatebetween approximately 2000 F at the top of the tank and 100 F at thebottom using boron oxide as a heat transfer fluid. The thermo-cline tank(17) is used to cool the hydrogen during charging and heat the hydrogenduring discharge.

A Stirling engine (20) is located next to the calcium/calcium hydridestorage tank (1). A metal vapor boiler and heat pipe/metal boiler (21)connects from the Stirling engine (20) into the inner tank (4).Magnesium vapor is used as a heat transfer fluid within the boiler andheat pipe (21).

The hydrogen lines are attached as follows:

-   -   1) Hydrogen inlet and outlet (11 a) connects from the reactor        (1) to the top of the thermo-cline heat exchanger (17). A        floating seal at the thermo-cline junction provides for thermal        expansion.    -   2) The bottom of the thermo-cline heat exchanger (17) connects        to the hydride tanks (2). The common hydride tank feed line is        (11F).

Water flowing through an underground heat exchanger is used to maintainthe hydride tank (2) temperature by circulating through a reservoirsurrounding the hydride tanks (2)

FIG. 2 shows an embodiment of the system where a heat pipe (10) isintegrated at the top of the hydride storage cell (1). In thisconfiguration the system behavior for the hydrogen flow and energy flowis identical to FIG. 1 where the solar heat is applied directly to thebottom of the reaction chamber (9). The difference is in the location ofthe solar heat target. For FIG. 1 the solar energy passes through thequartz window (15) and projects directly onto the bottom of the reactionchamber (9). This system requires that the solar input beam besubstantially vertical passing through the quartz window (15). Toaccomplish the solar heat input in FIG. 1 the side focusing helio-statsfirst create an approximately constant diameter sunlight beam of 12inches in diameter for the 100 kW system. Multiple beams, from the sidefocusing helio-stats, are reflected from individual down beam mirrorslocated directly above the quartz window (15). The design in FIG. 2eliminates the need for the down beam mirrors and allows the sidefocusing helio-stat beam to project directly on the side of the heatpipe (10) which is projecting from the top of the reactor (1). A quartzbell (7) is added over the heat pipe (10) to minimize thermal losses andprotect it from atmospheric corrosion. At night an insulation cover isfolded over the quartz bell (7) to minimize thermal losses.

Operation

The system operates in a charging mode and a discharging mode. Systemoperation can be maintained by controlling temperatures in both thecalcium reactor and titanium iron hydride storage tanks. The totalsystem can operate without valves so that the pressure is constantthroughout the system. Hydrogen pressure in the hydride storage (2),thermo-cline (17), and reactor (1) are constant as long as the flowrates are slow or stopped. Piping is sized to minimize pressure dropthrough the system while the hydrogen is flowing during normaloperation. The equilibrium hydrogen pressure is approximately 1atmosphere at 1800 F and 5 atmospheres at 2000 F in the calcium reactor(1) between the calcium, hydrogen, and calcium hydride. Belowequilibrium temperature the reaction is exothermic creating calciumhydride. Above equilibrium temperature the reaction is endothermiccreating calcium and hydrogen. As an example of system operation: if thepressure is approximately constant at 3 atmospheres then the equilibriumtemperature is approximately 1900 F. If the reactor (1) is heated by thesun then the temperature rises slightly and hydrogen is formed. The rateof hydrogen produced from the reactor (1) is a function of thetemperature above equilibrium. The hydrogen generation rate willincrease until a new equilibrium is reached in solar energy absorbed andthe energy required for the endothermic reaction. When the solar energyis reduced, at night or when a cloud passes overhead, then thetemperature drops within the calcium reactor (1) until a new equilibriumis reached in hydrogen flow. As the solar energy goes to zero then thetemperature drops to a point where hydrogen wants to flow back into thecalcium reactor (1). The hydrogen reacts with the calcium and creates anexothermic reaction which produces a new equilibrium temperature. Thesystem is designed so that all processes operate in the 1 to 5atmospheres and 1800 F to 2000 F reactor (1) temperature ranges. One ofthe features of this system is the automatic stability based on heatinput to the calcium reactor which allows the system to operate withouthydrogen flow rate controls.

The second part of the system is the hydrogen storage using an ambienttemperature hydride. Titanium iron hydride provides an ideal solutionfor the storage of hydrogen due to its ability to combine and releasehydrogen near ambient temperature conditions. The process is exothermicwhen hydrogen is combining to form the titanium iron hydride andendothermic when hydrogen is being released. Operating near ambientconditions allows this heat, to and from the titanium iron hydridereaction, to come from the surroundings so that extra energy is notrequired by the system. The movement of hydrogen in and out of thetitanium iron hydride is a function of the titanium iron hydridetemperature which also operates in an equilibrium condition. Theequilibrium pressure is approximately 1.5 atmospheres at 32 F and 5.5atmospheres at 86 F. To keep the hydrogen pressure below 5 atmospheresthe titanium iron hydride needs to be cooled during the day whilehydrogen is flowing into the titanium iron hydride powder as thisprocess is exothermic and releases heat. To maintain an approximatelyconstant temperature a flowing water bath (8) is used which surroundsmultiple tanks (2). The tanks (2) are positioned sideways, with thehydride powder filling approximately 70% of the volume, to allow forexpansion of the titanium iron hydride during the absorption process.Using the earth as a heat sink allows an almost constant temperature forboth day and night for the water bath (8). A temperature ofapproximately 60 F, based on an average ground temperature, allows thehydrogen equilibrium to stay near 3 atmospheres during the systemoperation.

Charging mode: During the daylight hours solar energy is available forthermal storage. The reaction of the calcium hydride breaking apart toform calcium and hydrogen is endothermic and absorbs the focused heatfrom the sunlight. A group of side focusing helio-stats direct the sunsenergy through the quartz window (15) and onto the reaction chamber (9).The equilibrium pressure for calcium hydride varies with temperature.The calcium and calcium hydride located in tank (4) is maintained atapproximately 1900 F by controlling the hydrogen pressure in storagecell (1) using the temperature of the titanium iron hydride tanks as anautomatic control system. Maintaining the same pressure in tanks (3A),(3B) and (4) eliminates the stress on the wall of tanks (4) and (3B) dueto the pressure. The tank (3A) is at low temperature and provides thestructure for the pressure. When solar energy is available to heat thecalcium reactor the temperature rises above equilibrium, for a givenpressure, which causes hydrogen to be released. The calcium temperatureis maintained using the energy balance between the incoming solarenergy, the calcium, and the hydrogen reaction rate and direction. Thetemperature increment above equilibrium increases the hydrogen flow rateuntil an energy balance occurs between the incoming solar energy and theendothermic reaction rate of the calcium and hydrogen evolution. Theprocess stabilizes automatically so that no valves or control system isrequired for the hydrogen flow. The hydrogen exits through the hydrogenoutlet (11 a).

The hydrogen exiting the hydrogen line (11 a) is at approximately 1900 Fand contains a substantial amount of thermal energy. The hydrogen flowsthrough the thermo-cline heat exchanger (18 a) and is cooled by theboron oxide in the thermal storage (17). The hydrogen temperature dropsfrom 2000 F to 100 F while the boron oxide is heated from 100 F to 2000F. Graphite fiber oriented perpendicular to the hydrogen flow increasesthe heat transfer within the boron oxide in the radial direction.Graphite has a much lower thermal conductivity perpendicular to thefiber direction. This allows the boron oxide to operate with the 1900 Ftemperature gradient within the tank with minimal thermal losses.

The temperature of the calcium/calcium hydride, is maintained atapproximately 1900 F in tank (4) by maintaining the hydrogen pressureabove the calcium to approximately 3 atmospheres. The system flow chartis shown in FIG. 4.

Discharge mode: The Stirling engine (20) extracts heat directly fromtank (4) which contains the calcium and calcium hydride. A heat pipe(21) connects to the hot side of the Stirling engine and passes throughthe outer tank lid (5) and into tank (4). Sufficient heat pipe area isextended within tank (4), or on the external surface of tank (4), toprevent the calcium hydride from solidifying around the heat pipe whilethe engine is extracting thermal energy.

The rate of hydrogen flowing out of the hydride tanks (2) is controlledby the temperature of the reaction chamber (1). As the calcium andcalcium hydride temperature drops the equilibrium pressure drops untilthe pressure in the reactor (1) falls below the hydride tank (2)pressure.

Hydrogen flows from the hydride tank (2) into the heat exchanger (18A).Passing through the heat exchanger (18A) heats the hydrogen toapproximately 1900 F where it then flows into the hydrogen inlet line(11 a). The temperature in the inner tank (4) is maintained atapproximately 1900 F by the hydrogen flow rate out of the hydride tank(2).

The system flowchart is shown in FIG. 3.

Variations to the Baseline System:

Different metals could be used in place of the calcium. These couldinclude: magnesium, strontium, barium, lithium, sodium, potassium,titanium, or zirconium. Also boro-hydrides could be used such aslithium, sodium, or potassium.

The system could operate without either the high temperature storagetank (17) or the low temperature storage tank (22). In this case asecondary cooling loop using an external heat exchanger with thesurroundings could be used such as with air, a solid heat sink, or watercooling.

Multiple heat engines or a single engine could be used to extract theheat from tank (4). The heat engines could include any variation ofbrayton, Stirling, or rankine cycles. A secondary steam cycle could alsobe used to supply peaking power utilizing a steam turbine.

An inert gas within tank (3A) could be nitrogen or argon instead ofhydrogen to reduce the heat loss. The gas in (3A) would not have thefilter (24) through the (3 b) wall.

The hydride storage material could be a number of hydrides including:Magnesium nickel hydride, lithium aluminum hydride, magnesium ironhydride, lanthanum nickel aluminum hydride, calcium nickel hydride,titanium iron hydride, or magnesium hydride. The hydrogen could also bestored as a compressed gas or liquid.

The system can be operated over a wider temperature range such as 1200 Fto 2500 F.

The system can operate with the temperature in tank (4) below 1800 F sothat the Calcium hydride is a solid.

A Kovar seal could be used to support reaction chamber (9) at the top oflid (5). Both the bolt flange (14 a) and the quartz window (15) holddown ring could be water cooled.

The nitrate salt mixture could use lithium nitrate instead of, or with,the calcium nitrate as a eutectic with the potassium and sodium nitratesalts.

For operation during long periods of cloudy weather a 2^(nd) heat sourceis required. One solution is to use a burner and air pre-heater assemblywhere the heat is directed into an exhaust heat exchanger to absorb thecombustion energy. A closed hydrogen loop between the calcium tank (1)and the exhaust heat exchanger would provide a technique to maintain thecalcium temperature. The hydrogen would be pumped in and out of theregion above the liquid calcium in tank (1) with the additional heatbeing extracted from the exhaust heat exchanger. Any type of fuel couldbe used for this purpose.

A variation on the quartz window (15) cover would be to use a 2 wayshape memory alloy attached to an insulated multi-segment door. Thesegments would be hinged against the top wall of the reaction chamber(9). During daylight hours heating from the sun would cause the memorymetal to flex downward opening the segments by rotating the insulationup against the reaction chamber (9) wall so that sun could enter. Atnight the cooling from lack of sunlight would cool the memory metal andit would flex to rotate the insulation segments so as to close the lidwhich reduces thermal loss at night.

CONCLUSIONS

The thermal storage system provides a unique and significant advantagein that it provides a continuous low cost high energy density controlsystem. Integration of these features allows economically viable storagesystems over a much broader size range than existing storage systems.The claims provide details of how the unique features are integratedinto a complete system.

1. A solar energy collection and storage system including: A device forfocusing solar energy, or any type of thermal energy, into a reactionchamber for the conversion of metal hydride to liquid metal andhydrogen, a metal/metal hydride vessel containing a metal/metal hydridemixture, a hydrogen storage system.
 2. The system of claim 1 wherein themetal is selected from the group of calcium, magnesium, strontium,barium, lithium, sodium, potassium, titanium, or zirconium.
 3. Thesystem of claim 1 wherein the hydride is selected form the group ofmetal boro-hydrides of lithium, sodium, or potassium.
 4. The system ofclaim 1 wherein the reaction vessel is at the focus of a helio-stat orfield of solar mirrors.
 5. The system of claim 1 wherein the reactionvessel has a quartz window and a molybdenum conduit projecting withinthe metal/metal hydride so that sunlight can project onto the bottom ofthe conduit for heating the metal/metal hydride.
 6. The system of claim1 wherein the reaction vessel has a heat pipe projecting out of the topof the reaction vessel with the heat pipe also extending into themetal/metal hydride for heating the metal/metal hydride.
 7. The systemof claim 1 wherein a heat transfer conduit projects through reactor lidand into the metal/metal hydride.
 8. The system of claim 1 wherein ahydrogen flow line projects into the reactor vessel.
 9. The system ofclaim 1 wherein the metal/metal hydride pressure vessel is locatedwithin an outer pressure vessel and an annular space exists between themetal hydride pressure vessel and the inner wall of the outer pressurevessel.
 10. The system of claim 1 wherein the metal/metal hydride iscontained within an inner metal or ceramic vessel, a mid metal containersupports the inner vessel, and an outer pressure vessel supports boththe inner and mid vessels.
 11. The system of claim 1 wherein the innervessel is fabricated from molybdenum with a lanthanum oxide dispersion.12. The system of claim 1 wherein the inner vessel is fabricated from acalcium aluminate or calcium oxide ceramic.
 13. The system of claim 1wherein the inner vessel is fabricated with an internal metal wire meshwhich is covered with ceramic creating an enhanced structural innervessel.
 14. The system of claim 1 wherein the inner vessel is supportedby a rigid or powdered ceramic such as silicon dioxide or aluminum oxideor calcium oxide.
 15. The system of claim 1 wherein a primary gas streamextends from the reaction chamber to a hydrogen storage vessel.
 16. Thesystem of claim 1 wherein a primary gas stream extends from the reactionchamber through a heat transfer thermocline to a hydrogen storagevessel.
 17. The system of claim 1 wherein hydrogen storage systemcomprises one or multiple hydrogen storage vessels, the hydrogen storagematerial comprising a metal or metal alloy capable of reacting with orabsorbing hydrogen.
 18. The system of claim 1 wherein the hydridestorage material is at least one metal hydride selected from the groupof magnesium nickel hydride, lithium aluminum hydride, magnesium ironhydride, lanthanum nickel aluminum hydride, calcium nickel hydride,titanium iron hydride, and magnesium hydride.
 19. The system of claim 1wherein multiple hydride storage vessels are contained within a watercooled tank.
 20. The system of claim 1 wherein the hydrogen storagesystem is hydrogen stored as a compressed gas or liquid.
 21. The systemof claim 1 wherein a heat exchanger and heat storage system is providedto recover heat from the primary hydrogen gas stream between thereaction chamber and the hydrogen storage vessel.
 22. The system ofclaim 1 wherein the heat changer material is boron oxide.
 23. The systemof claim 1 wherein the heat exchanger has graphite fiber, dispersedwithin the boron oxide, oriented predominantly sideways relative to thedirection of hydrogen flowing within multiple heat transport tubes withthe heat exchanger operating as a thermo-cline.
 24. The system of claim1 wherein the boron oxide, in the heat exchanger, flows within a counterflow heat exchanger transferring heat with the hydrogen gas.
 25. Thesystem of claim 1 wherein the heat exchanger consists of a high and lowtemperature tanks system with separate heat transfer materials handlinga high and low temperature hydrogen temperature range.
 26. The system ofclaim 1 wherein the 2^(nd) heat exchanger utilizes a nitrate saltmixture from the group of alkaline metal nitrates.
 27. The system ofclaim 1 wherein the heat exchange occurs with the hydrogen gas withoutmixing between the hydrogen gas and the heat exchange materials.
 28. Thesystem of claim 1 wherein the hydrogen gas flows from the hydrogenstorage system into the reactor providing a chemical reaction with themetal to create the hydride and thermal energy.
 29. A thermal storagemethod wherein energy is stored when a compound of two or more materialsare separated into components. Said components operate reversibly sothat when they combine they release thermal energy and when they areseparated they absorb thermal energy. Said components store their energyin the heat of formation differences between the individual materials orelements and the compound which is formed when they are broughttogether.
 30. The method of claim 29 wherein one of the components ishydrogen and the second component is a metal with the metal remaining inthe reactor and the hydrogen being transported to a separate container.31. The method of claim 29 wherein the hydrogen is cooled by flowing thehydrogen through a heat exchanger, with the energy stored in a separatethermal storage container, before the hydrogen is stored.
 32. The methodof claim 29 wherein the hydrogen is stored within a hydride materialwhich can reversibly release the hydrogen when required.
 33. The methodof claim 29 wherein the hydride material uses a flowing liquid reservoirsurrounding the storage vessels, such as water, to maintain a constanthydride temperature.
 34. The method of claim 29 wherein the flowingliquid, used to maintain the hydride storage tanks, uses the thermalheat capacity and temperature of the ground, to maintain the hydridestorage tank temperature.
 35. The method of claim 29 wherein the metalhydride sinks below the metal surface providing a fresh surface for thehydrogen reaction to occur.
 36. The method of claim 29 wherein thehydrogen pressure is used to control the rate and direction of theexothermic and endothermic processes.
 37. A thermal storage systemwherein the process of separating two materials provides a means for thestorage of thermal energy in chemical form. Said materials releaseenergy when they are recombined. The direction of said materials tocombine or separate is determined by the hydrogen gas pressure at aconstant operating temperature.